1. Field of the Invention
The present invention relates to a sole which forms each bottom of footwear such as running shoes and walking shoes, and footwear provided with such soles.
2. Description of the Related Art
As a sole which forms each bottom of footwear, for example, Patent Document 1 discloses a sole which includes a mid-sole and a plurality of out-soles joined to the bottom surface of the mid-sole substantially over its whole area. Each out-sole is flat in the width directions thereof and becomes gradually thinner from the rear end toward the front end thereof.
In this sole according to Patent Document 1, when the out-soles touch the ground, then the center of gravity is guided forward and further ahead, thereby prompting the forward propulsion movement. This makes it possible to move the center of gravity smoothly in the front and back directions.
In general, a person walks or runs by landing in order from the heel toward the toes on the ground and leaving the ground successively from the heel toward the toes so that the center of gravity can be moved. It is known that at this time, a foot pressure center alike which corresponds to the center of a pressure applied to each foot bottom passes from the heel through the toes, especially the big toe pad. This foot pressure center's locus is an important element which represents the rightness of a walking or running motion.
However, in a pair of shoes provided with the soles according to Patent Document 1, when a person walks or runs with the shoes on, because the out-soles are joined over substantially the whole area of the mid-sole and are flat in the width directions, the foot pressure center passes on an individually different route in accordance with a personal walking or running motion. Hence, a desirable movement route of the foot pressure center is left out of account.
On the other hand, in recent years, how footwear affects the skeletal structure or muscles of a human body's lower half has increasingly become a matter of importance. At the same time, a variety of research and development has become active, aiming at a smooth and quick walking or running motion. There is a great demand for shoes or the like for making optimum walking and running motions.
It is an object of the present invention to provide a sole which is capable of properly controlling the movement of a foot pressure center using a simple configuration, and footwear provided with such soles.